GreenPois0n RC6.1 has been released for iOS 4.2.1, the untethered jailbreak includes an update that resolves the iBooks DRM issue that caused some iOS jailbreakers from losing access to certain protected iBooks.

I tried RC6 and RC6.1 for apple TV 2g running IOS 4.2.1 and the “JailBreak Complete!” box has been grey out for a long time. What is happening? I tried the same step several times and got the same result each time and I have to press “Quit” button to start over.